Lightweight valves of the kind referred to here are known (DE 198 04 053 A1). They are used inter alia as inlet and outlet valves for internal combustion engines and comprise a valve stem which is adjoined by a funnel/trumpet-shaped valve cone. For the purpose of weight reduction, the valve cone is hollow and has only a small wall thickness. The valve cone is closed at its end of greater diameter by means of a valve disk. Furthermore, the valve stem has a hollow space at its end facing the valve disk, by virtue of which the weight of the lightweight valve is further reduced.
As the valve disk is not supported on a large area owing to the hollow space in the valve cone and the valve cone moreover has only a small wall thickness, the valve disk may be deformed during operation by the combustion pressure in the combustion chamber of the internal combustion engine, which contributes to premature wear of the lightweight valve. Furthermore, the thin-walled valve cone may also be deformed. In order to prevent this, DE 198 04 053 A1 proposes making the valve stem so long that it rests with its end face on that flat side of the valve disk facing away from the combustion chamber, by virtue of which the disk is supported. In this connection, the valve stem, which is hollow or made of solid material, and the valve disk can be welded together in their contact region. An alternative proposal is to manufacture the valve stem and the valve disk in one piece, that is as one part. In other alternatives, the valve disk is supported against the valve stem by means of an intermediate piece designed in one piece on the valve cone or a separate sleeve fixed between valve stem and valve disk. It is a disadvantage of the known lightweight valves that their individual parts can in some cases be produced only in a costly way owing to their geometry which is defined by the construction concerned and that accurate alignment of the individual parts in relation to one another before the joining process can be brought about only with high outlay.